Решение на рисунке, надеюсь разборчиво.
B^2 - 9y^2 : 4b^2 +12by+9y^21) 5(x+4y)/ 15(x+4y) = 1/3
2) <span>8a^2+40ab : ab+5b^2 = 8a (a + 5b) / b(a+5b) = 8a/b
3) </span><span>8ab : 4a^2 b^2+8ab^3 = 8ab / 4ab^2 (a +2b) = 2/b (a+2b)
4) </span><span>x^2 -9 : 4x-12 = (x-3)(x+3) / 4(x-3) = x+3/4
5) </span><span>3a+15b : a^2 - 25b^2 = 3(a+5b) / (a-5b)(a+5b) = 3/a+5b
6) </span> y^2<span>+4y+4 : y^2 +2y = (y+2)^2 / y(y+2) = y+2/y
7) </span><span>b^2 +10b+25 : b^2 -25 = (b+5)^2 / (b-5)(b+5) = b+5/b-5
</span><span>4b^2 - 9y^2 : 4b^2 +12by+9y^2 = (2b-3y)(2b+3y)/ (2b+3y)^2 = 2b-3y/2b+3y = 2*(-1/4) - 3* (5/6) / 2*(-1/4) - 3*(-5/6) = -0.5 + 2.5 / -0.5 +2.5 = 2/2 = 1</span>